Multipole circuit breaker



Feb. 28, 1967 l.. E. cooPr-:R 3,307,002

MULTIPOLE CIRCUI T BREAKER Filed Feb. 4, 1965 6 Sheets-Sheet 1 Feb. 28, 1967 L. COOPER I* MULTI-POLE CIRCUIT BREAKER 6 Sheets-Sheet 2 Filed Feb. 4, 1965 4//r "f z l x I I t l n@ mw. @Q m mi S @E mw mw /m\ 6 Sheets-Sheet 3 Feb. 28, 1967 L. E. COOPER MULTIPOLE CIRCUIT BREAKER Filed Feb. 4, 1965 Feb. 28, 1967 .L -E. COOPER MULTIPOLE CIRCUIT BREAKER 6 Sheets-Sheet 4 Filed Feb. 4, 1965 Feb. 28, 1967 L. E. COOPER 3,307,002

MULTIPOLE CIRCUIT BREKER i med Feb. 4, 1965 e sheets-sheet 5 (n SS if@ d U DISTANCE 33H05 NINSdO lDVlNO Feb. 28, 1967 1 E. COOPER MULTIPOLE CIRCUIT BREAKER 6 Sheets-Sheet 6 Filed Feb. 4, 1965 www MN RY www/M nited States Patent fifice l 3,307,002 y MULTIPGLE'CIRCUIT BREAKE Lawrence E. Cooper, Attleboro, Mass.,l assignor to Texas Instruments Incorporated, Dallas, Tex., a corporation of Delawarev Filed Feb. 4, 19,65, Ser. No. 430,423 Y 16 Claims. (Cl. 204)?116) v -This inventionrelates" to circuit breakers and more particularly -to multipolecir'cuit breakers which are responsive to an overload current lpassing through any one ofthe poles to openall of thev circuits. In the development of multipole circuit breakers, particularly those employing trip-free mechanisms such as that shown in ULS. Letters Patent 2,613,296 issued on October 7, 1952, to M. B. Wood, therehas been a continuing problem in achieving complete independence in the sensitivities of the different mechanisms, that is, the currentpassing through one of the poles should not affect the trip point of the others. Complete independence is a highly desirable characteristic, particular-ly for circuit breakers used. in polyph'ase A.C. circuits aboard aircraft. A related problem is that of insuring that all poles will open under so-called hot-reclose conditions in which an attempt is made to reset the circuit breaker while one or`more of the poles is in a trip condition. It is highly desirable to render it impossible for any of the poles to be reset when one'of them is in trip condition or, stated conversely, no fewer than all of the poles lshould ever be reset.

Among the several objects of the invention may be noted the provision of a mult-ipole circuit breaker whi-ch is responsive to an overload current passing through any one of the poles to open all of the circuits; the provision of such .a circuit breaker in which the trip threshold for each pole is independent of the current level passing through any other pole; the provision of such a circuit breaker in which no fewer than all of the poles can be reset; the provision of such a circuit breaker which is eX- tremely reliable; the provision of such.=a circuit Ibreaker which operates quickly; and the provision of such a circuit bre-aker which is of relatively simple `and inexpensive construction. Other objects .and features will be in part apparent and in part pointed out hereinafter.

In one aspect a circuit breaker according to the present invention involves a plurality of trip-free circuit breaking mechanisms which are arranged side by side and are-resettable by means of a common manually operable member.' Each of the mechanisms includes a fixed contact and a movable contact member having a movable contact adapted for engagement with the fixed contact. The contact member is movable between a first position in which the contacts .are separated and a second position in which the fixed and movable contacts are in conductive engagement. A biasing means normally urges the movable contact member towards the first position. Each mechanism also includes a displaceable reaction force bearing member, a latch for restraining movement of the reaction member, Iand current responsive means for releasing the latch. A driving or wedging member is provided Which is adapted to be driven lagainst the reaction member for moving the contact member to its second position when the latch is not released.

When one of the mechanisms is tripped by a current overload, the other mechanisms are tripped substantially simultaneously by coupling means, operative between each pair of adjacent mechanisms ment of either of the contact members thereof upon tripping of the respective mechanism, which transmits the movement of the driving member of the tripped mechanism to the latch of any untripped adjacent mechanism. In order to provide a sufficient force for tripping adjacent and4 responsive to movei B'd Patented Feb. 28, 1957 mechanisms upon hot reclose conditions, the biasing means for each mechanism has a rate characteristic providing a contact opening force at the point of cross tripping Iwhich is greater than 13/30 of the forceexerted when the contacts `are closed.

The invention accordingly comprises the construction hereinafter described, the scope of the invention being indicated in the following claims.

A`In the accompanying drawings in which several of various possible embodiments of the invention are illustrated,

FIG. l is a side view of a three pole circuit lbreaker in which three single pole circuit breaking mechanisms are arranged side by side, parts being broken away to show the components of the mid le mechanism, the components being in a normal Contact open configuration;

FIG. 2 is a simiiar view with the parts in contact closed position;

FIG. 3 is a similar view with the parts in .trip-free position;

FIG. 4 is a view substantially on the line 4-4 of FIG. 3, the casing being partially broken away to show la slide for coupling one mechanism to another;

FIG. 5 is a View substantially on the line 5-5 of FIG. 1, the casing being broken away at different levels to show various components of the individual breaker mechanisms;

' FIG. 6 is a section on the line 6 6 of FIG. 5;

FIG. 7 isa side view similar to FIG, 1 showing a modification employing `a toggle lever spring arrangement;

FIG. 8 is a similar View showing another modification which employs a tape-like linear spring;

FIG. 9 is a similar view showing another modification employing magentic biasing;

FIG. 10 is a graph illustrating the rate characteristics of the different biasing means employed in the various modifications of FIGS. 1-9;

FIG. 11 is a side view with parts broken away of an embodiment in which the latches of adjacent mechanisms are coupled together with a lost motion connection;

FIG. 12 is a section substantially on the line 12-12 of FIG. 11;

FIG. 13 is a view essentially similar to FIG. 12 showing a modification; and F IG. 14 shows a further modification.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Referring now to the drawings, the multipole circuit breaker illustrated in FIGS. 1-6 is made up of three complete single pole circuit breaking mechanisms 11, 13 and 15, each of which is assembled in a respective casing 17, These casings are molded of a suitable insulating plastic material with appropriate recesses and the like for retaining the parts of the mechanism described hereinafter. Casings 17, 19 and 21 are assembled in a side-by-side relationship with cross pins 22. A common face plate 24 covers all three casings. In FIGS. 1-3 the that the components of the middle visible. The construction of in the following description of the arrangement of the individual mechanisms, the other two mechanisms lbeing essentially similar.

Extending through the bottom of each casing, as viewed in FIGS. 1-3, are two terminals 23 and 2S. Each terminal 23 is connected to a fixed Contact 27 within the respective casing. An arm 29, which is pivotally mounted on a pin 31 fixed within the respective casing, carries a movable contact 33 for movement from a first position in which the contacts 33 and 27 are separated to a second position in which they are in conductive engagement. A suitable arc chute (not shown) can be incorporated if desired. Also pivotally mounted on pin 31 is a cam member 35. By means of facing lip portions 37 and 39 on contact arm 29 and cam member 35 respectively, a lost motion connectionv for rotation is established between these elements. This lost motion connection is biased by a coiled compression spring 41, cam member 35 and contact arm 29 being urged away from each other.

A coiled tension spring 43 has one end xed relative to the respective casing by attachment to a pin 45. The other end of spring 43 is attached to the cam member 35 and urges'the rotating assembly, which includes the movable contact 33, to the rst position in which the movable contact is separated from lixed contact 27. It should be noted that a plurality of springs 43 may be used in each mechanism and that such a multiple spring construction may be useful in obtaining various spring rate characteristics for the purposes described hereinafter.

A displaceable reaction force bearing member 47 constitutes a third element which is pivotally mounted relative to the casing on pin 31. Bearing member 47 is mounted on pin 31 by means of a slotted aperture 49 so as to provide room for lost motion. Reaction member 47 is normally urged in a counterclockwise direction, as viewed in FIGS. l-3, by a tension spring 51 whose fixed end is mounted relative to the casing on a pin 53. Rotation of reaction member 47 in the clockwise direction is selectively limited by a latch member 55, reaction member 47 including a projection 57 for engagement with an abutment 59 on latch member 55. Latch member 55 is pivotally mounted on a pin 6i) and is normally urged into engagement with reaction member 47 lby a compression spring 61.

In the embodiment illustrated, there are provided two separate current responsive means for releasing the latch, a U-shaped bimetal element 63 and a generally U-shaped electromagnet structure 65. The electromagnetic structure 65 includes a pair of poles 67 and 69 which project into a magnetically coupled relationship with latch member 55. Pole 67 serves alsol as a guide for spring 61. Latch member includes an arm portion 71 whichyis constructed of a bimetal laminate toprovide ambient temperature compensation. The arm includes a projection 73 adapted to be engaged by bimetal element 63. Bimetal element 63 is constructed so that, when it is heated, its free end moves to the right into engagementv with the projection 73 on arm 71, thereby -rotating the latch member 55 in a clockwise direction and releasing reaction member 47. It the ambient temperature is high the projection 73 is moved away from bimetal element 63 by bimetal arm 71 so'that the net heating which must be applied to element 63 to trip the mechanism remains substantially constant.

Bimetal element 63 and magnet 65 are connected for energization in a circuit joining the movable contact 33 to the terminal 25 as follows: movable contact 33 is connected to the tree end of bimetal element 63 by a fiexible braid lead 75 which does not restrict the movement of either element. The fixed end of bimetal element `63 is welded to an electrically conductive mount 77. The mount includes an arm 79 into which is threaded a screw 81. The head ofV the screw rotates freely within a vrecess in the casing. By means of this screw the nominal position of bimetal element 63 can be adjusted for calibration of the trip threshold in conventional manner. Mount 77 is in turn welded to a bus bar 83. Bus bar 83 is a metal stamping of convoluted form which, as viewed in FIGS. 1 3, passes under pole 67 and over pole 69 so that the magnetic fields created in these poles by a current passing through the bus bar will aid each other in attracting latch member 55. Bus bar 83 is insulated from the poles 67 and 69 by plastic collars 85. The bus bar 83 is welded at its lower end to the terminal 25.

Each of the mechanisms 11, 13 and 15 includes a respective operating plunger 87, 89 and 91 which is, as viewed in FIGS. 1 3, slidingly mounted in the respective casingr for movement on a vertical axis passing through pin 31. The plunger S9 for the middle one of the three circuit breaker mechanisms extends through the cover plate 24 and terminates in a push button 92 for the manual operation of the breaker. `The-plungers 87 and 91 for the outer mechanisms are coupled to the center plunger 89 by a cross bar 93 (FIG. 5). Each plunger 37, 89 .and 91 has pivotally attached thereto, by means of apin 94, a pair of swinging links 95. `The links 95 in each mechanism are maintained parallel to one another by a cross-brace pin 97 which is rigidly connected to each link. Between each such pair of links 95 are mountedthree rollers 99, 191 and 103 on an axle -pin V105. The middle roller lill in each mechanism is of smaller diameter than the outside rollers 99 and 103 which are of equal diameter. The rollers and the links in each mechanism constitute a driving or wedging member 106 adapted to be driven against reaction member 47 and between it and the respective cam member.

The operation of each of the mechanisms 11, 13 and 15 is essentially as follows, the center mechanism 13 visible in FIGS. l-3 again being taken as an example. In FIG. l the parts areshown in their normal open positions, the button 92 being retracted and the movable contact 33 being pulled to its rst position away from the fixed contact 27 by spring 43. To close the contacts the push button 92 is depressed so that the rollers 99 and 103 engage the surface of cam` member 35 while the middle ork smaller roller 99 engages the reaction force bearing member 47. Assuming that the bimetal element 63 is cool, the clockwise movement of the reaction member 47 is limited by the engagement of projection y57 against the abutment 59 of the latch member 55. Thus, the continued downward movement of -operating plunger 89' will cause the rollers 99, 101 Iand l103 to wedge between reaction member 47 and cam member 35 thereby rotating the cam member, with its associated movable contact 33, in a counterclockwise direction against the tension of spring 43. It should at this point be noted that the force exerted by spring 43 is transmitted through driving member 166 to reaction member 47 and the reaction member applies this force to the latching surface between projectionf57and abutment 59. The total force applied to the latching engagement is a parameter affecting the force required to releasethe latchy and hence it also affects the sensitivity or trip threshold of the mechanism. Accordingly, the force exerted by springs 43 at the contacts closed position is not arbitrarily variable but is, in large extent, dictated by the'overall design of the breaker and particularly of the current responsive cornponents which initiate the tripping operation.

When movable contact 33 initially engages fixed contact 27, the cam member 35 can continue to move by compressing `spring 41 ,until -the parts reach the positions shownin FIG. 2. It should be noted that the configuration shown in FIG. 2 'is stable because the cam member 35 and reaction'member 47 are so shaped that they cooperate in retaining the rollers, there being no net upward for-ce applied through links 95 to plunger 89. With the parts so positioned a current can be passed through the breaker mechanism from terminal 23 to terminal 25.

If acurrent somewhat greater than a preselected value is passed through one of the mechanisms, the respective bimetal element 63 will gradually heat and, due to the bimetal construction, its free end will gradually move to the right coming into engagement with projection 73 on arm 7l. The latch member 55 will thus be rotated clockwise around to the pin 60 thereby releasing the reaction member 47. Latch 55 can also be tripped to release reaction member 47 by the application of a current which is so much greater than the preselected ultimate trip threshold that the electromagnet 65 is sufficiently energized to attract latch member 55. This feature provides a very rapid release in case of suddenly applied currents which greatly exceed the ultimate trip threshold.

Upon the release of the latch member 55, spring 43 will cause the cam member 35, the rollers 99, 101 and 103, and the reaction member 47 to rotate, substantially as a unit, in a clockwise direction around pivot pin 31. After the rst bit of rotation has taken up the lost motion permittedby lips 37 and 39, contact arm 29 will be picked up by cam member 35 so that the movable contact 33 is moved out of engagement with the xed contact 27. It should be noted that the' separation of the contacts is initiated by the impact of lip 39 coming into engagement with lip 37 so that a very rapid contact opening is provided. l If the push button 92 is held down, the elements rotating about pin 31 continue substantially to the positions shown in FIG. 3. This is the trip-free position in which the contacts are open even though the button is depressed. It may be seen that the rollers 99, 101 and 103 are somewhatlwithdrawn from their position between cam member 35 and reaction member 47 since their path of movement is restrained by the limited length of the links 95.

It should be noted that, when the parts are in the position shown in FIG. 3, there is an upward force applied to plunger 89, through the rollers and links 95, by spring 51. Accordingly, ,if push button 92 is not restrained, the elements rearrange themselves into the positions shown in FIG. l so that the protruding button gives a visual indication that the breaker has been tripped and so that the breaker is ready to be reset. In returning to the position shown in FIG. l, the reaction member 47 does not have to displace latch member 55 or compress spring 61 in order for the projection 57 to clear latch abutment 59. Rather, the clearance is provided by taking up the lost motion permitted by slotted aperture 49.

As discussed previously, it is an object of the present invention to open all of the circuits if any one of them is overloaded and yet allow each of the mechanisms to operate independently in the manner just described so that the trip threshold for each circuit is independent of the magnitude of current owing through any of the other circuits. The latch member 55 of each of the mechanisms normally operates at relatively low force levels. Thus loading of these elements before tripping should therefore be avoided since it would cause a shift in the trip threshold. In the embodiment of the invention illustrated in FIGS. 1-6, energy for tripping the untripped circuits is obtained from lthe driving or wedging member 106 of the tripped pole. The driving member operates at relatively high force levels. Upon tripping, it is moved to the right (clockwise around pin 31) under the influence of the spring 43 which opens the contacts.

The energy for cross tripping is transmitted between adjacent mechanisms by slides 113 which are supported for transverse movement in channels 115 formed into the abutting side walls of adjacent casings. The slides are best seen in FIGS. 4, 5 and 6, although they can also be seen in back of the mechanism components in FIGS. 1-3 through a Window 119 which opens from each of the channels 115 into the main chamber of each of the adjacent casings and through which access may be had from each mechanism to the slide. It may be noted that FIG. 6 shows the slide from the same side as FIG. l but with the breaker mechanism components removed from view. For transmitting lateral movement of the driving or wedging members 106 to each adjacent slide 113, the respective axle pin 105 extends through the respective window 119 so as to be engageable with a shoulder 121 on the slide 113. It should be noted that the shoulders 121 extend vertically for the entire height of the slide so that the vertical excursions of the wedging member can be accommodated. For receiving the cross tripping movement, each of the latch members 55 includes a projection 123 extending laterally through each adjacent window 119 so as to be engageable by a shoulder 125 on slide 113. The slides 113 are normally biased to the left, that is away from engagement with the latch projection 123, by springs 127. This bias tends to prevent tripping of the breakers by vibration acting on the slides.

When one of the mechanisms is tripped, its wedging member 106 moves to the right as explained previously. The respective axle pin will drive the slide 113 to the right and, if the adjacent mechanism is not already tripped, the slide will release the untripped latch. Since either of the adjacent .mechanisms can drive one of the slides 113 by means of the respective axle pin 105 and since the 'slide can engage and release the latch 55 of either of the adjacent mechanisms, it can be seen that the tripping of any lone of the mechanisms will trip any previously untripped adjacent mechanism. It can also be seen that, since either latch extension 123 can freely move away from the respective slide shoulder 125, the latches 55 are not loaded in any way bythe slides 113. Thus each of the mechanisms 11, 13 and 15 will truly operate independently of the others and the trip threshold for each will not be influenced by the ,level of current passing through any of the other circuits.

In achieving proper operation upon current overload conditions, it is necessary that the springs 43 exert a force which is sucient not only to open the contacts of the respective breaker but also to trip any previously untripped adjacent mechanisms. In particular, the center mechanism 13 of the three must develop suicient force to trip both of the side mechanisms 11 and 15. This requirernent is not particularly 'severe under overload conditions when the breaker mechanisms trip from a closed circuit position since, in that case, the components of the tripped mechanism are in rapid movement when the point of cross tripping of adjacent mechanisms is reached. The latches of the adjacent mechanisms are thus displaced with an impact and not merely under the influence of the contact opening springs 43 of the tripped mechanism. However, it has been found that this requirement is significantly more severe under so-called hot-reclose conditions, that is, when an attempt is made to reset the circuit breaker while one of the mechanisms is still in a tripped condition. In this situation, the reaction member 47 of the tripped mechanism is not restrained by its respective latch 55. Therefore when button 92 is depressed, the elements of the tripped mechanism proceed directly from the configuration shown in FIG. 1 to the positions shown in FIG. 3, without the respective contacts ever being closed. In other words, as the wedging member 106 is driven between cam member 35 and reaction member 47, it is the reaction member rather than the cam member which is primarily displaced.

As the wedging rollers move down the surface of cam member 35, they and their axle pin 105 will move to the right, `as seen in FIGS. l-3, thereby displacing the adjacent slides 113. When the point of cross tripping for adjacent mechanisms is reached, it is essential that it be the reaction member rather than the cam member 35 which is displaced by the continued downward movement of the wedging member. Otherwise the adjacent breakers will not be tripped and their contacts will be closed even though the contacts of the one breaker are not closed. In order for cam member 35 to resist movement under these conditions, it is necessary that the springs 43 exert a force which is suiiicient, when transmitted through wedging member 106, to displace the slides 113 and to trip all previously untripped adjacent mechanism. In the popular form of trip-free mechanism illustrated, it has been found that, to insure satisfactory operation under hot-reclose conditions, the force exerted by springs 43 at the point of cross tripping of adjacent mechanisms should be greater than 1%@ of the force exerted when the contacts are closed.

One way of obtaining such a rate characteristic using a linear coil spring would be to use a relatively long spring so that the ratio of the spring extensions in the two signiicant positions is |substantially equal to the desired force ratio. However, as a practical matter, such an approach cannot be used if the casings are to be kept within conventlional established dimensions.

In the embodiment illustrated in FIGS. 1-6, the springs 43 have been Agiven the desired rate characteristics by Winding the coils under torsion lso that the spring exhibits a substantial force preload which must be overcome before any extension at all is obtained. The rate characteristic of this preloaded spring is shown in the Igraph of FIG. l as line B. The length of the spring when fully extended, that is in contacts closed position, is taken as unity on the horizontal scale while the free or unextended length of the spring is approximately 0.47. The ratio of these lengths is of course in large extent determined by the space availablewithin the pre-established dimensions of the casing. The point of cross tripping of adjacent mechanisms occurs when springs 43 are exten-ded only slightly so that their length is 0.6 of the length Lof the fully extended spring. yIt will be noted that the force exerted by this spring at the point of cross tripping is slightly greater than 1%@ of the force exerted when the contacts are closed. This rate characteristic may be compared with that of a conventional coil spring having no preload as illustrated in FIG. l() by the line A in which the force applied rises linearly from zero starting at the free length of the spring.

' The desired rate characteristic for the contact opening force can also be provided byemploying the modilied construction illustrated in FIG. 7. In this arrangement, the contact carrying cam member 35 is urged in a clockwise direction around pin 31 by a compression spring 135 rather than a tension spring as illustrated in the previous example. The sprin-g 135 extends from a locating boss 137 on a side wall of the casing to a projection 139 on arm 35. The attachments at each end of spring 135 are arranged, in cooperation with the natural flexibility of the spring, so thata substantially pivotal connection is established. It can thus be seen that spring 135 and cam mem-ber 35 essentially constitute a toggle linkage. With such an arrangement, spring 135 operates on a varying ymoment arm to rotate cam member 35 around pin 31. Accordingly a highly nonlinear force characteristic is obtained which tends to otiset the decreasing force available from spring `135 as it extends. The net contact opening force obtained with this arrangement is illustrated in FIG. l() by the line C. It will be noted that this curve exhibits a peak at about 0.65 on the horizontal scale where the product of the spring force and the effective moment arm reach a maximum. rangement and for the following mo'dications have been plotted on the 'graph of FiG. 10 in terms of equivalent contact positions so that comparisons can be easily made.

Another modification, which is capable of providing a substantially uniform contact opening force, is shown in FIG. 8. In this embodiment the cam member 35 is urged upwardly by a tape-like spring member 141 attached thereto by a rivet 143. The tape-like spring member 141% given a preset so that, when it is unstressed, it returns to an arcuate or coiledconiiguration. The upper end of spring member 141 is permitted to coil around a freely turning guide wheel 145 journaled in the casing on a pin 147. Accordingly, as the cam arm 35 is moved downwardly in closing the circuit, progressive portions of the tape-like spring member are straightened. The for-ce necessary to so strai'ghten progressive portions of the tapelike spring member is only that necessary to overcome `the lpreset of the naturally arcuate spring at the point where it leaves 4guide wheel 145. Since this force is substantially constant in a tape-like spring lmember of uniform width and thickness, a substantially constant contact opening force is obtained. This rate characteristic is illustrated on the graph FIG. 10 bythe line D. j

A fourth method of obtaining adequate force at the point of cross tripping is to supplement the spring characteristics with magnetic attraction as illustrated in FIG. 9. In this embodiment, the cam arm is urged upwardly by a spring 43 as in the example shown in FIG. 1. HOW- ever, cam arm 35 also carries an armature piece 151 secured thereto by rivet 153. A permanent magnet is mounted on a post 157 extending from the casing toward the path of the armature. As cam arm 35 passes through the point of cross tripping and approaches the fully open position, the magnetic attraction between the magnet 155 and armature 151 will increase rapidly thereby causing the net contact opening force to increase nonlinearly as illustrated by the line E in the -graph of FIG. l0.

It will-be noted that, in each of the examples whose contact opening force characteristics are illustrated by the lines B through E, the force available at the point of cross tripping of adjacent breakers is greater than 13/30 of the force provided when the contacts are closed, the curves 'being referenced to unity at this point for comparison purposes. In the embodiments shown in FIGS. 7, 8 and 9, the force ,characteristics are such that, as illustrated by the lines C, D and E, the force at the point of cross tripping is essentially not less than the force exerted when the contacts are closed.

FIGS. l1 and l2 illustrate a modiiication in which the force for tripping adjacent mechanisms is obtained from the reaction force 4bearing `member of a tripped mechanis-m rather than its driving or wedging member. In this embodiment the reaction force bearing member 47' includes a projection 161 which is adapted to strike a surface 163 on latch 55 when the mechanism is tripped. Each of the latch members 55' inclu-des a projection 165' extending laterally toward the adjacent mechanisms. The projections extending toward each other on a` pair of adjacent breakers are coupled by a lost motion connection constituted by a collar 167 which is xedly attached to one of the projections 165 and which loosely contines the movement of the other (FIG. l2).

Since there is lost motion in the connection between adjacent latches 55', the current responsive elements in each of the -mechanisms needs only to deflect the respective latch, the lost motion being sufficient to accommodate the motion necessary for the independent tripping of either of the adjacent mechanisms. The latch in each mechanism is thus not loaded `by the latches of any of the others and the trip thresholds for each mechanism are not affected by conditions in the others. However, upon tripping of one mechanism, the projection 161 on the'respec'tive reaction member 47 will strike the already The rate characteristic for this artripped latch member 55, driving it further in the direction of tripping. This additional movementtakes up the lost motion travel and causes movement to be transmitted from the tripped latch to the latch of anypuntripped adjacent mechanism. Accordingly these adjacent mechanisms will be tripped substantially simultaneously with the mechanism in which the original tripping current overload occurs.

In place of using a collar 167 which is attached to one of the latches 55 the lost motion connection can also be provided by a slide similar to that used in the embodiment of FIG. l. In the modification illustrated in FIG. 13 a slide 169 is mounted for lateral movement in a channel 171 formed in the casing walls between adjacent mechanisms. The slide includes a'pair of back-to-back slots 173 for receiving the adjacent latch projections 165. The slots 173 are of such width that sufficient lost motion is provided in the connection between the projections 165 so that each latch 55 can be operated completely independently by its respective current responsive components. Upon tripping, however, the additional displacement of the tripped latch caused by the impact of the respective reaction member will cause a tripping motion to lbe transmitted through the slide to the untripped latch. The modification-illustrated in FIG. 14 represents a combination of the coupling arrangement illustrated in FIG. 13 with that employed in the embodiment of FIGS. 1-6. In FIG. 14 there is shown a slide 177 mounted for lateral movement as in the previous examples. The slide includes a pair of shoulders 121 adapted -for engagement by the driving member axles 105 of a pair of adjacent breakers as well as slots 173 providing a lost motion connection between adjacent latch projections 165. In this way the latch of an untripped mechanism, which is adjacent a mechanism fbeing tripped, can be tripped by movement transferred from either the driving member of the tripped mechanism or by the movement of the respective reaction force bearing member as transmitted through the respective latch and the slots 173. This arrangement thus provides redundant means of cross tripping for increased reliability.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could 'be made in the above constructions without departing from the scope of the invention, it isl intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

' What is claimed is:

1. A multipole circuit breaker comprising: l a plurality of trip-free circuit breaking mechanisms arranged side by side each of which includes a fixed contact, a movable con-tact member including a movable contact adapted Ifor engagement with said fixed contact, said member being movable between afirst position in which said contacts are separated and a second position in which said contacts are in conductive engagement, biasing means urging said contact member toward said first position, a displaceable reaction force bearing member, a latch for 'restraining movement of said reaction member, current responsive means for releasing said latch upon passage through said contacts of a current greater than a predetermined level, and a driving member adapted to be driven against said reaction member thereby to move said contact member to said second position when said reaction member is restrained by said latch, the force of said biasing means being transmitted through said driving member to said latch; and l `a slide operative lbetween each pair of adjacent breaker mechanisms, each being slidable generally transversely of the direction of movement of said driving members which moves said contact ymembers to said second positions, each said slide having first surface means engageable by and responsive to movement of either of the respective driving members upon tripping of the respective mechanism and second surface means engageable with either of the respective latches for transmitting movement from the driving member of a tripped one of said mechanisms to the latch of any untripped adjacent mechanism thereby to trip such untripped mechanism, the position of the contact member which produces tripping of adjacent mechanisms constituting a point of cross tripping for the member, said biasing means having rate characteristics providing a contact opening force at said point which is greater than 1%@ of the force exerted when the contacts are closed whereby, if said driving members are driven against the respective bearing members while one mechanism is still in tripped condition following an overload, the spring means of said one mechanism will poss-ess `sufficient force to permit the respective driving member to trip all adjacent mechanisms substantially simultanesaid contact member so that 1.-@ ously thereby preventing closing of any of the mechanisms until all of them can be closed.

2. A multipole circuit breaker as set forth in claim 1 including spring means for biasing said slide against movement caused by vibration.

3. A multipole circuit breaker as set forth in claim 1 in which said biasing means includes a coiled tension spring, the coils of which are wound under torsion whereby said spring exhibits a rate characteristic having a substantial force preload which must be overcome before any extension is obtained.

fi. 'A multipole circuit breaker as set forth in claim 1 in which said biasing means includes a tape-like spring member which, when unstressed, returns to an arcuate configuration, one end of said tape being connected to movement of said contact member toward said second position straightens progressive portions of said tape-like member.

S. A multipole circuit breaker as set forth in claim 1 in which said biasing means includes permanent magnet means exerting a nonlinear force tending to hold said contact member in said first position.

6. A multipole circuit breaker as set forth in claim 1 in which said contact member is movable about a pivot and said biasing means includes a compression spring one end of which is pivotally mounted at a fixed pivot and the other end of which is attached to said contact member, said spring and said contact member constituting a toggle linkage providing a nonlinear Contact opening force.

7. A multipole circuit breaker as set forth in claim 1 in which said biasing means provides a contact opening force at said point of cross tripping which is not less than the force exerted when the contacts are closed.

3. A multipole circuit breaker comprising:

a plurality of trip-free circuit breaking mechanisms arranged side by side each of which includes a fixed contact, a movable contact member including a movable contact adapted for engagement with said fixed contact, said member being movable between a first position in which said contacts are separate-d and a second position in which said contacts are in conductive engagement, a tape-like spring member for urging said contact member toward said first position, said spring member being preformed to normally assume an arcuate configuration, one end of said spring member being connected to said contact member so that movement of said Contact member toward said second position straightens progressive portions of said spring member, a displaceable reaction force bearing member, a latch for restraining movement of said reaction member, current responsive means for releasing said latch upon passage through said contacts of a current greater than a predetermined level, and a driving member adapted to be driven against said reaction member thereby to move said contact member to said second position when said reaction member is restrained by said latch, the force exerted by said spring member being transmitted through said driving member to said latch; and

means, operative between each pair of adjacent breaker mechanisms and responsive to movement of either of the respective contact members thereof upon tripping of that mechanism, for transmitting movement from the driving member of that one of said mechanisms to the latch of any untripped adjacent mechanism thereby to trip each mechanism whereby, when one of said mechanisms is tripped by a current overload, all of the contacts will bey opened.

9. A multipole circuit breaker comprising:

a plurality of trip-free circuit breaking mechanisms arranged side by side each of which includes a fixed contact, a movable contact member inopening force, a dispiaceable reaction force bearing member, a latch for restraining movement of said reaction member, current responsive means for releasing said latch upon passage through said contacts of a current greater than a predetermined level, and a driving member adapted to be driven against said reaction member thereby to move said contact member to saidy second position when said reaction member is restrained by said latch, the force of said spring being transmitted through said driving member to said latch; and

means, operative between each pair of adjacent breaker mechanisms and responsive to movement of either of the respective Contact members thereof upon tripping of that mechanism, for transmitting movement from the driving member of that one of said mechanisms to the latch of any untripped adjacent mechanism thereby to trip such mechanism whereby, when one of said mechanisms is tripped by a current overload, all of the contacts will be opened.

1t). A multipolecircuit breaker comprising: a plurality of trip-free circuit breaking mechanisms arranged side by side e-ach of which includes a fixed contact, a movable contact member including a movable contact adapted for engagement with said fixed contact, said member being movable between a tirst position in which said contacts are separated and a second position in which said vcontacts are in conductive engagement, a spring urging said contact member toward said iirst position, a magnet exerting a nonlinear force tending to hold said contact member in said lirst position, a displaceabie reaction Jioree bearing member, a latch for restraining movement of said reaction member, current responsive means for releasing said latch upon passage through said contacts of a current greater than a predetermined level, and a driving member adapted to be driven againstl said reaction -member thereby to move said contact member to said second position when said reaction member is restrained by said latch, the force exerted by said spring being transmitted through said driving member to said latch', and

means, operative between each pair of adjacent breaker mechanisms and responsive to movement of either of the `respective contact members thereof upon tripping of that mechanism, for transmitting movement from the driving member of that one of said mech- Vanisms to the 4latch of any untripped adjacent mechanism thereby to trip such mechanism whereby, when yone of said mechanisms is tripped by a current overload, all of the'contacts will be opened and if said -driving members are driven against the respective bearing members while one mechanism is stiil in tripped condition following an overload, the magnet will exert sufficient force to permit the respective driving member to trip all adjacent mechanisms thereby preventing closing of any of the mechanisms until all of them can be closed.

11. A multipole circuit breaker comprising: :a plurality of trip-free circuit breaking mechanisms ar- .ranged side by side each of `which includes Cil t i2 a lixed contact, a movable contact member including a movable contact adapted forzengagement with said fixed contact, said member being movable between a first position in which said contacts are separated and a second position in which said contacts are in conductive engagement, biasing means urging said contact member toward said first position, a displaceable. reaction force bearing member, a latch for restraining movement of said reaction member, current responsive means for releasing said latchupon passage through said contacts of a current greater than a predetermined level, and means for moving said contact memberto said second position when said reaction member is restrained by said latch, said reaction memberincluding a portion which, upon release of said `reaction member by said latch, engages and drives said latch further in the directionof release', and means for establishing a lost-motion connection between the latches of adjacent mechanisms whereby each of said latches functions independently within the limits of the lost motion in tripping the respective mechanism but, upon tripping there-of, is driven beyond the limits of the lost motion by theI respective reaction member and thereby trips the latches of any untripped adjacent mechanisms. l i2. A multipole circuit breaker comprising: a plurality of trip-free circuit breaking mechanisms arranged side by side each of which includes a fixed contact, a movable contact member including a movable contact adapted for engagement with said fixed contact, said member being movable between a tirst position in which said contacts are separated` and a second position in which said contacts are in conductive engagement, biasing means urging said contact member toward said first position, a displaceable reaction force bearing member, a latch for restraining movement of said reaction member, current responsive means for releasing said latch upon passage through said contacts of a current greater than a predetermined level, and a driving member adapted to be driven against said reaction member thereby to move said contact member to said second position when said reaction member isrestrained by said latch, said reaction member including a portion which, upon t release of said reaction member by said latch, engages and drives said latch further in the direction of release; and means for establishing a lost-motion connection between the latches of adjacent mechanisms whereby 'each of said latches functions independently within the limits of thelost motion in tripping the respective mechanism but, upon tripping thereof, is driven beyond the limits of the lost motion by the respective reaction member and thereby trips the latches of any untripped adjacent mechanisms. i3. A multipole circuit breaker as set forth in claim 12 in which each of the latches includes a projecting portion extending laterally toward each adjacent mechanism and in which the connection means includes a coupler mem-y pair of adjacent mechanisms, said coupler member being xed to one of the laterally opposing projecting portions and loosely confining the other of said projecting portions in the direction of release thereby to provide said lost-motion connection between the respective latches.

14. A multipoie circuit breaker as set forth in claim 12 in which each of the latches includes a projecting portion extending laterally toward each adjacent mechanism and in which said mechanisms are enclosed in a housing and the connection means comprises a slide mounted in said housing between each pair of adjacent mechanisms,

ber positioned between each 13 said slide including recesses on opposite sides thereof for loosely engaging the laterally opposed projecting portions extending from said pair of breakers thereby to provide said lost-motion connection between the respective latches.

15. A multipole circuit breaker as set forth in claim 14 in which said slide is also adapted to be engaged by the driving member of either of said pair of mechanisms upon tripping thereof thereby to releaseI the latch of the other of said pair of mechanisms.

16. A multipole circuit breaker as set forth in claim 12 further comprising means, operative between each pair of adjacent mechanisms and responsive to tripping of that mechanism, for transmitting movement from the driving member of that one of said mechanisms upon tripping to the latch of any untripped adjacent mechanism thereby to trip such mechanism.

References Cited by the Examiner UNITED 4/1950 10/1952 8/1954 l1/l957 11/1960 1l/l960 7/1964 3/1965 3/1965 STATES PATENTS Platz et al. 200-116 Wood 20G-116 Straub et al. 200-ll6 Mascioli et al. 200-116 X Brackett ZOO-116 Wood 20G-116 Brackett 200*l16 Powell 200-116 Beaudoin 20G-166 BERNARD A. GILHEANY, Primary Examiner. 15 H. B. GILSON, Assistant Examiner. 

1. A MULTIPOLE CIRCUIT BREAKER COMPRISING: A PLURALITY OF TRIP-FREE CIRCUIT BREAKING MECHANISMS ARRANGED SIDE BY SIDE EACH OF WHICH INCLUDES A FIXED CONTACT, A MOVABLE CONTACT MEMBER INCLUDING A MOVABLE CONTACT ADAPTED FOR ENGAGEMENT WITH SAID FIXED CONTACT, SAID MEMBER BEING MOVABLE BETWEEN A FIRST POSITION IN WHICH SAID CONTACTS ARE SEPARATED AND A SECOND POSITION IN WHICH SAID CONTACTS ARE IN CONDUCTIVE ENGAGEMENT, BIASING MEANS URGING SAID CONTACT MEMBER TOWARD SAID FIRST POSITION, A DISPLACEABLE REACTION FORCE BEARING MEMBER, A LATCH FOR RESTRAINING MOVEMENT OF SAID REACTION MEMBER, CURRENT RESPONSIVE MEANS FOR RELEASING SAID LATCH UPON PASSAGE THROUGH SAID CONTACTS OF A CURRENT GREATER THAN A PREDETERMINED LEVEL, AND A DRIVING MEMBER ADAPTED TO BE DRIVEN AGAINST SAID REACTION MEMBER THEREBY TO MOVE SAID CONTACT MEMBER TO SAID SECOND POSITION WHEN SAID REACTION MEMBER IS RESTRAINED BY SAID LATCH, THE FORCE OF SAID BIASING MEANS BEING TRANSMITTED THROUGH SAID DRIVING MEMBER TO SAID LATCH; AND A SLIDE OPERATIVE BETWEEN EACH PAIR OF ADJACENT BREAKER MECHANISMS, EACH BEING SLIDABLE GENERALLY TRANSVERSELY OF THE DIRECTION OF MOVEMENT OF SAID DRIVING MEMBERS WHICH MOVES SAID CONTACT MEMBERS TO SAID SECOND POSITIONS, EACH SAID SLIDE HAVING FIRST SURFACE MEANS ENGAGEABLE BY AND RESPONSIVE TO MOVEMENT OF EITHER OF THE RESPECTIVE DRIVING MEMBERS UPON TRIPPING OF THE RESPECTIVE MECHANISM AND SECOND SURFACE MEANS ENGAGEABLE WITH EITHER OF THE RESPECTIVE LATCHES FOR TRANSMITTING MOVEMENT FROM THE DRIVING MEMBER OF A TRIPPED ONE OF SAID MECHANISMS TO THE LATCH OF ANY UNTRIPPED ADJACENT MECHANISM THEREBY TO TRIP SUCH UNTRIPPED MECHANISM, THE POSITION OF THE CONTACT MEMBER WHICH PRODUCES TRIPPING OF ADJACENT MECHANISMS CONSTITUTING A POINT OF CROSS TRIPPING FOR THE MEMBER, SAID BIASING MEANS HAVING RATE CHARACTERISTICS PROVIDING A CONTACT OPENING FORCE AT SAID POINT WHICH IS GREATER THAN 18/30 OF THE FORCE EXERTED WHEN THE CONTACTS ARE CLOSED WHEREBY, IF SAID DRIVING MEMBERS ARE DRIVEN AGAINST THE RESPECTIVE BEARING MEMBERS WHILE ONE MECHANISM IS STILL IN TRIPPED CONDITION FOLLOWING AN OVERLOAD, THE SPRING MEANS OF SAID ONE MECHANISM WILL POSSESS SUFFICIENT FORCE TO PERMIT THE RESPECTIVE DRIVING MEMBER TO TRIP ALL ADJACENT MECHANISMS SUBSTANTIALLY SIMULTANEOUSLY THEREBY PREVENTING CLOSING OF ANY OF THE MECHANISMS UNTIL ALL OF THEM CAN BE CLOSED. 